Calculate the power requirements for lifting 40 kg sacks of cement up 1 m at the rate of 1 sack/second. If you had a team of superworkers who could do this all day long, how many would it take to equal the power available from the hydroelectric system of Exercise 1.3? Using a good current working wage, calculate the cost of the energy provided by these humans in, for example, $/J and compare that to the current cost of electrical energy in your area. What does this lead you to conclude about society’s need for energy conversion technology?

Data From Exercise 1.3

Let V be the water velocity in a river of width w and depth d, flowing along at a height h above a hydraulic power station. Show that the maximum electrical power that could be obtained by converting the potential energy of the river water to electrical energy is ρ · ν · w · d · h · g, where ρ is the water mass density. Calculate the maximum available power (MW) for ω = 20 m, d = 10 m, h = 100 m, Ѵ  = 2 m/s, using ρ = 1000 kg/m³.